1. Field of the Invention
This invention relates to spacecraft and launch systems and, more specifically, to reusable spacecraft for servicing earth-orbiting satellites and other near-earth craft.
2. Description of Related Art
The history of current space vehicle technology is a history of high expense and high material waste. The first vehicles put into space were orbital capsules where the technology required to launch them vertically from the ground and into orbit was 10 times the size of the actual craft. To achieve a Low Earth Orbit (LEO)—where a vehicle can stay aloft—the first rocket left Earth in several stages. The amount of fuel used to propel the rocket was determined by the weight of the capsule and its payload (which included the fuel it needed to sustain its orbit), the weight of the propellant rockets, and the weight of the fuel itself before lift-off. A certain amount of the rocket assembly was destroyed in the launch, and the remaining parts burned up in the atmosphere once the capsule was delivered to LEO. All that returned to Earth was the orbiting capsule with its payload. Low Earth Orbit is only about 60 miles above the surface of the Earth. To put a satellite into an orbit that is stable requires going approximately 250 miles above ground. That requires more fuel, thus more or bigger rockets.
As craft were designed to reach our moon, the expense increased dramatically. For any vehicle to proceed beyond LEO, it must carry within it the fuel needed to complete its mission and return with its payload. That increased fuel greatly added to the weight the rockets had to launch. Along with the increased size and weight of the rockets came an increased fuel need, and the costs increased exponentially. And still, only a fraction of the capital investment returned to Earth, unable to be reused.
The U.S. Space Shuttle was designed to be reusable, but still requires rockets much larger than the craft itself to launch. It also costs about $10,000 per pound of payload to complete a mission-and that's every time a launch occurs, since the vast majority of capital goes into a product which primarily gets burned up or is otherwise unable to be reused. The current U.S. Space Shuttle requires 30–40 tons of material to be used each time it's launched, all of which is rebuilt and refinanced each time. Moreover, the launch facilities required for such enormous vertically launched rocket vehicles require a capital investment that only the wealthiest countries can afford. Thus the present state of the art has reached a ceiling and prohibits any commercial ventures by all but a few nations in the world.